Epidemics

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Epidemics

• Pedro Ribeiro de Andrade
• Gilberto Câmara

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Epidemic
In epidemiology, an epidemic occurs when new
cases of a certain disease, in a given human
population, and during a given period,
substantially exceed what is expected based on
recent experience.
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Source Viboud and Chowell (NIH)
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Source Viboud and Chowell (NIH)
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Source Viboud and Chowell (NIH)
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Source Viboud and Chowell (NIH)
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Source Viboud and Chowell (NIH)
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Source Viboud and Chowell (NIH)
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Source Viboud and Chowell (NIH)
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Source Viboud and Chowell (NIH)
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Epidemic dynamics (SIR model)
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Epidemic dynamics (SIR model)
S(t) is used to represent the number of
individuals not yet infected with the disease at
time t I(t) denotes the number of individuals who
have been infected with the disease and are
capable of spreading the disease to those in the
susceptible category. R(t) is the compartment
used for those individuals who have been infected
and then recovered from the disease. Those in
this category are not able to be infected again
or to transmit the infection to others.
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Source Viboud and Chowell (NIH)
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SIR model
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SIR model in discrete time
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Parameter calculation
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Source Viboud and Chowell (NIH)
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Epidemic dynamics (SIR model)

• Stocks susceptible, infected, and recovered
• Initial stocks susceptible 999, infected 1
• Infectious period 4 days
• Run time 100 days
• Each infected contacts 1 other people each day
• 40 of the contacts cause infection

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